CSM and epoxy, the two can not be done together?

Discussion in 'Fiberglass and Composite Boat Building' started by coolgps, Nov 26, 2012.

  1. coolgps
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    coolgps Junior Member

    I was told it was a convention that CSM(chopped strand mat) can not go with epoxy, but the teller can not explain why.
    The powder or emulsion in CSM will react with epoxy? Or epoxy can not wet CSM very well? I had infused CSM with vinyl ester resin before, the look was not good.
    Otherwise, the saying is nonsense.
     
  2. fcfc
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    fcfc Senior Member

    See http://www.westsystem.com/ss/chopped-strand-mat-epoxy/

    The other issue is why do you need CSM with epoxy ?

    With polyester resin, you need CSM between biaxial/roving layers to increase bonding/shear between the layers. But epoxy has enough mechanical properties not to need CSM.

    Also, with polyester, you need CSM outer layers, because polyester resin retracts while curing, and will cause print thru. Epoxy does not retracts on curing.

    So, what is the purpose of CSM ?
     
  3. TeddyDiver
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    TeddyDiver Gollywobbler

    It won't dissolve to epoxy..
     
  4. PAR
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    PAR Yacht Designer/Builder

    All binders and sizing used on CSM is compatible with epoxy. Technically, there are some that can cause issues, but these aren't very common and you'd have to look really hard to find any.

    The sizing melts and becomes part of the resin/hardener mixture in polyester/vinylester laminates, but with epoxy, some of the sizing types just remain in suspension.

    Simply put, the notion that these sizing/binder materials don't work with epoxy, is just the inexperience of the polyester product seller showing. It doesn't matter at all, if the sizing is melted or in suspension.

    As previously mentioned, why would you use CSM in an epoxy laminate? It's unnecessary, nor very desirable with epoxy.
     
  5. coolgps
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    coolgps Junior Member

    Recently, we are making epoxy carbon fiber molds for a prepreg boat. First layer is one woven e-glass fabric 300, it is done with hand laminate, it didn't look decent with lots of void, maybe bad laminator is one part of it. So we want to use CSM300 to replace woven fabric, then i am told CSM does't go with epoxy.
    Thank you all, your explanations help me a lot.
     
  6. PAR
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    PAR Yacht Designer/Builder

    CSM isn't a replacement for fabric. If you have these types of basic laminating questions, maybe a discussion with the boat's designer is in order,. A laminate schedule change such as this (replacing cloth with CSM), is a huge structural downgrade and if you're laminating experience suggests this is reasonable, good luck with your insurance, once those products hit the water. The same is true with the myths about CSM and epoxy. First of all, you don't need or want CSM in an epoxy laminate and second it sticks just fine, in fact, far better than any other resin system. If you are having issues with these basic epoxy and laminating processes, then please find a laminate processional, familiar with the products you're using to guide you, as it scares the hell out of me that these sort of "decisions" might actually get produced and sold to unknowing boaters. Simply put, carbon laminates are highly engineered and guessing isn't the best way to go about getting this done. Now, I realize you've come here to get some advise, but the laminate designer's office is the place you need to have this discussion. Lastly, if you're having voids and other issues with a carbon pre-peg layup, you can pretty much bet it's not the materials, but the laminator.
     
  7. coolgps
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    coolgps Junior Member

    If it is a boat lamination, sure we can not change it by our own. But it is just for mold surface fairing, maybe it is no harm to replace it? Thanks for you advice.
     
  8. Frosty

    Frosty Previous Member

    I have nothing at all to add because I have no idea what CSM is.

    I would like to know and follow the conversation. For the sake of people that have other skills can we give up abbreviation on a world wide forum please.

    I assume it is not a Cold sausage muffin,-- but then it could be.
     
  9. coolgps
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    coolgps Junior Member

    hahahaha~~Funny one,:D:D:D:D. CSM is short for Chopped strand mat.
     
  10. FMS
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    FMS Senior Member

    Anyone who has worked with fiberglass in the past will know the term CSM. Chopped Strand Mat was one of the three basic materials. Brand new guys might not know it with Epoxy the goo of choice now.
     
  11. Frosty

    Frosty Previous Member

    Exactly--Im not a laminator but ide still like to read whats going on.

    FMS--- Faulty Management System?
     
  12. FMS
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    FMS Senior Member

    Describe in more detail exactly what you are doing. It's unclear to me whether the CSM/epoxy question is regarding the mold or the part/boat.
     
  13. PAR
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    PAR Yacht Designer/Builder

    CSM can be used to advantage in a mold, to ease fairing, though the original question suggested a pre-peg and I assumed a structure other than a mold, my apologies.

    I think a finishing cloth of lighter weight would work well for this. The OP mentioned an 8.8 ounce E glass (300 GSM), which is a bit heavy. A 4.5 ounce (150 GSM) or lighter cloth (such as a 70 - 80 GSM cloth) would be more suitable for finish work and would require much less resin to wetout and fill as well. Considering the amount of fairing usually required in a mold, the point seems moot, unless of course you have laminate issues (voids, poor wetout, etc.). These are process issues, not material related.
     
  14. Herman
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    Herman Senior Member

    Just to top it up: also get a decent laminator, that can impregnate and bubble bust a WR300 well. I also suspect your resin might be on the thin side. How about infusing the whole lot?
     

  15. fcfc
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    fcfc Senior Member

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